Looking Up: Enjoying Orion’s star-studded belt

If Orion changed to wearing suspenders, the constellation would never be the same again.

Peter Becker

If Orion changed to wearing suspenders, the constellation would never be the same again.

Step out the next clear night, in late January about 9:30 p.m., face south and look about halfway up.

Bursting forth from the dark of night is the glorious stars of Orion, one of the most recognized and celebrated constellations of the entire heavens.

Orion, the mythical Hunter, can be seen anywhere on Earth. The three conspicuous “belt stars” straddle the Celestial Equator. This imagined line encircles the sky midway from the North Celestial Pole, where the North Star resides right nearby, and the South Celestial Pole, seen Down Under. In other words, if you were on the ice of the North Polar Cap, right at the North Pole, the Celestial Equator exactly follows your horizon, and the North Star gleams almost exactly straight overhead. Orion’s northern half will be seen riding around the horizon as the 24 hours of night proceeds.

Likewise, in July when night covers Antarctica, from the South Pole you would see Orion’s southern half ride the horizon, upside down from what you are used to seeing from the United States.

The three belt stars of Orion are actually part of a loose stellar association, a wide-open star cluster with a common origin, moving in space in tandem. From left to right, the stars have Arabic names: Alnitak (”Girdle”), Alnilam (”Belt of Pearls”) and Mintaka (”Belt”).

These stars are at nearly the same distance from us (from left, 800, 1,000 and 900 light years). They are blue-white giant stars, each about 20 times the mass of the sun. They shine at +2nd magnitude (+6th is the usual lower limit of visibility to unaided eyes).

Look for Mintaka’s +7th magnitude companion star, with binoculars. Long-exposure photographs reveal that Alnitak is bathed in a faint cosmic cloud, or nebula, which includes the famous “Horsehead Nebula.” The cloud of black dust, superimposed on background nebula that is lit by star shine, its equine silhouette is unmistakable. Large backyard telescopes (10-inch aperture and bigger) can reveal it under very good sky conditions, and it is one my goals to catch this horsey!

Look also for an S-shaped line of stars that starts above Mintaka and sweeps down and ends between Alnilam and Alnitak. Binoculars are needed if moonlight is an issue.

A group of stars seem to hang below Alnitak and are known as Orion’s Sword. The middle “star” appears fuzzy in binoculars; this is the Great Nebula of Orion (also known as M42), breathtaking in even a small telescope. Stars are being formed within this nebula.

Other principal stars in Orion is the brilliant blue-white Rigel at lower right of the Belt and the fiery red-orange, brilliant Betelgeuse at upper left of the Belt. They mark corners of a huge, rough rectangle, with the Belt in the middle.

While we think of Orion as a mythical Hunter, thanks to the Greeks, the Belt Stars are referred to as the Saucepan (with the Sword stars) in Australia and New Zealand; as the Three Marys in Latin America; and as the Three Kings or Three Sisters in South Africa. The Bible refers to Orion in Job 9:9, Job 38:31 and Amos 5:8.

First-quarter moon is on Jan. 23; full moon is on the 30th.

Contact the writer at pbecker@wayneindependent.com.

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